今天我們一樣還是透過 CursorInfo 查詢

並取得 key.annotated_decl

key.annotated_decl

但是，查詢對象改為 DispatchQueue.main.async 的 async

DispatchQueue.main.async { ... }

<Declaration>
    func async(
        group: <Type usr=\"c:objc(cs)OS_dispatch_group\">DispatchGroup</Type>? = nil, 
        qos: <Type usr=\"s:8Dispatch0A3QoSV\">DispatchQoS</Type> = .unspecified, 
        flags: <Type usr=\"s:8Dispatch0A13WorkItemFlagsV\">DispatchWorkItemFlags</Type> = [], 
        execute work: @escaping @convention(block) () -> <Type usr=\"s:s4Voida\">Void</Type>
    )
</Declaration>

取得 value(原始定義)

func async(
    group: DispatchGroup? = nil, 
    qos: DispatchQos = .unspecified, 
    flags: DispatchWorkItemFlags = [], 
    execute work: @escaping @convention(block) () -> Void
)

Function Call Expr

透過解析 Function Call Expr 取得 last(index)/first name

比較麻煩的是 closure 在 function call 會有三種表示方式。

trailing closure

async {}

labeled closure

async {
} label: {
}

normal closure

async({})

Get index(name)

• trailing closure
  • args.last
• labeled closure
  • args["label"]
• normal closure
  • args["label"]
  • 有可能遇到無參數名稱

遇到無參數名稱，以及有預設值情況下難以判斷

解析是否是 escape

於是我們再將定義拿去 visitor parse 一遍

func async(
    group: DispatchGroup? = nil, 
    qos: DispatchQos = .unspecified, 
    flags: DispatchWorkItemFlags = [], 
    execute work: @escaping @convention(block) () -> Void
)

取得

• type: trailing closure
• name: execute
• index: last(3)
• type: @escaping @convention(block) () -> Void

進一步 Parsing

@escaping @convention(block) () -> Void

判斷目標:

• @escaping
• (closure)，例:
  • (() -> Void)
• objc closure(@convention(block))